How far a color sits from neutral gray at the same lightness: its intensity, from fully muted to the most vivid version a display can show.
Drop the saturation on the secondary buttons: they’re competing with the one action that should read as primary.
Saturation is the loudness knob, and an interface is conversation, not concert: text, surfaces, and borders live near gray so the single saturated action can carry the hierarchy. Two cautions. Desaturated is not the same as quiet: a pale screen can still be cluttered. And on today’s wide-gamut displays, “fully saturated” is louder than it was on the sRGB monitor where your taste was calibrated.